package main

import (
    "fmt"
    "runtime"
)



func main(){
    fmt.Print("Go runs on")

    switch os:= runtime.GOOS; os{
    case "darwin":
        fmt.Println("OS X.")
    case "linux":
        fmt.Println("Linux. ")
    default:
        fmt.Printf(" %s\n", os)
    }
}
